Autonomous driving system

ABSTRACT

An autonomous driving system includes a lane change control device that performs lane change control for making a lane change from a first lane to a second lane during autonomous driving of a vehicle. The lane change control device is configured to: determine, from start to completion of the lane change control, whether or not a driver&#39;s operation is performed as an abort request operation that requests to abort the lane change control; when the abort request operation is performed, determine whether or not an abort permission condition is satisfied; when the abort permission condition is not satisfied, continue the lane change control; and, when the abort permission condition is satisfied, abort the lane change control and make the vehicle travel in the first lane. The lane change control device changes ease of satisfaction of the abort permission condition depending on the situation.

BACKGROUND Technical Field

The present disclosure relates to an autonomous driving technique for avehicle. In particular, the present disclosure relates to lane changecontrol in autonomous driving.

Background Art

Patent Literature 1 discloses a technique relating to overtaking controlduring autonomous driving. According to the technique, an autonomousdriving system determines not to execute the overtaking control or toabort the overtaking control, depending on a situation of a followingvehicle and so forth.

LIST OF RELATED ART

-   Patent Literature 1: Japanese Laid-Open Patent Publication No.    2016-002892

SUMMARY

Let us consider a case where an autonomous driving system plans a lanechange and performs lane change control. In this case, there is apossibility that a driver has an intention to abort the lane changecontrol by the autonomous driving system. However, according to thetechnique disclosed in Patent Literature 1 described above, it is notpossible to reflect the driver's intention to abort in the lane changecontrol by the autonomous driving system.

An object of the present disclosure is to provide a technique that canreflect a driver's intention to abort in lane change control by anautonomous driving system.

A first disclosure provides an autonomous driving system mounted on avehicle.

The autonomous driving system includes:

a lane change control device that performs lane change control formaking a lane change from a first lane to a second lane duringautonomous driving of the vehicle; and

a driver's operation detection device that detects a driver's operationby a driver of the vehicle.

The lane change control device performs:

abort request detection processing that, from start to completion of thelane change control, determines whether or not the driver's operation isperformed as an abort request operation that requests to abort the lanechange control;

condition determination processing that, when the abort requestoperation is performed, determines whether or not an abort permissioncondition is satisfied; continuation processing that, when the abortpermission condition is not satisfied, continues the lane changecontrol; and

abort processing that, when the abort permission condition is satisfied,aborts the lane change control and makes the vehicle travel in the firstlane.

The lane change control device changes ease of satisfaction of the abortpermission condition depending on at least one of a type of the abortrequest operation, an operation amount of the abort request operation,an operation speed of the abort request operation, and a purpose of thelane change.

A second disclosure further has the following feature in addition to thefirst disclosure.

The lane change control device changes the ease of satisfaction of theabort permission condition depending on the type of the abort requestoperation.

A third disclosure further has the following feature in addition to thesecond disclosure.

The driver's operation detection device includes a turn signal lever anda steering wheel.

The abort permission condition when the turn signal lever is used forthe abort request operation is more easily satisfied than the abortpermission condition when the steering wheel is used for the abortrequest operation.

A fourth disclosure further has the following feature in addition to thethird disclosure.

A direction from the second lane to the first lane is an abortdirection.

The abort request operation using the turn signal lever is to operatethe turn signal lever to indicate the abort direction.

The abort request operation using the steering wheel is to steer thesteering wheel in the abort direction.

A fifth disclosure further has the following feature in addition to thethird or fourth disclosure.

When the abort request operation is performed after the vehicle overlapsthe second lane and when the abort permission condition is satisfied,the lane change control device performs return control that makes thevehicle return from the second lane to the first lane.

A travel path of the vehicle in the return control is a return path.

The return path when the turn signal lever is used for the abort requestoperation is shorter than the return path when the steering wheel isused for the abort request operation.

A sixth disclosure further has the following feature in addition to thethird or fourth disclosure.

When the abort request operation is performed after the vehicle overlapsthe second lane and when the abort permission condition is satisfied,the lane change control device performs return control that makes thevehicle return from the second lane to the first lane.

Acceleration/deceleration of the vehicle in the return control is returnacceleration/deceleration.

The return acceleration/deceleration when the turn signal lever is usedfor the abort request operation is higher than the returnacceleration/deceleration when the steering wheel is used for the abortrequest operation.

A seventh disclosure further has the following feature in addition tothe first disclosure.

The lane change control device changes the ease of satisfaction of theabort permission condition depending on the operation amount or theoperation speed of the abort request operation.

An eighth disclosure further has the following feature in addition tothe seventh disclosure.

A direction from the second lane to the first lane is an abortdirection.

The driver's operation detection device includes a steering wheel.

The abort request operation is to steer the steering wheel in the abortdirection.

The abort permission condition becomes more easily satisfied as asteering amount of the steering wheel becomes larger or a steering speedof the steering wheel becomes higher.

A ninth disclosure further has the following feature in addition to thefirst disclosure.

The lane change control device changes the ease of satisfaction of theabort permission condition depending on the purpose of the lane change.

A tenth disclosure further has the following feature in addition to theninth disclosure.

The abort permission condition when the purpose is overtaking is moreeasily satisfied than the abort permission condition when the purpose islane merging, lane branching, or obstacle avoidance.

An eleventh disclosure further has the following feature in addition toany one of the first to tenth disclosures.

An abort-permitted region is a region where abort of the lane changecontrol is permitted.

The abort permission condition is that the vehicle is inside theabort-permitted region.

When increasing the ease of satisfaction of the abort permissioncondition, the lane change control device expands the abort-permittedregion.

When decreasing the ease of satisfaction of the abort permissioncondition, the lane change control device narrows the abort-permittedregion.

A twelfth disclosure further has the following feature in addition toany one of the first to tenth disclosures.

The abort permission condition is that a congestion level of asurrounding vehicle traveling in the first lane is less than athreshold.

When increasing the ease of satisfaction of the abort permissioncondition, the lane change control device increases the threshold.

When decreasing the ease of satisfaction of the abort permissioncondition, the lane change control device decreases the threshold.

As described above, the autonomous driving system according to thepresent disclosure is configured to be able to handle the abort requestoperation by the driver from start to completion of the lane changecontrol. When the abort request operation is performed by the driver andthe abort permission condition is satisfied, the autonomous drivingsystem aborts the lane change control. As a result, the driver'sintention to abort is reflected in the lane change control by theautonomous driving system.

Furthermore, according to the present disclosure, the ease ofsatisfaction of the abort permission condition is changed depending onat least one of “the type of the abort request operation”, “theoperation amount of the abort request operation”, “the operation speedof the abort request operation”, and “the purpose of the lane change”.Each of the type, the operation amount, and the operation speed of theabort request operation reflects strength of the driver's intention toabort. By changing the ease of satisfaction of the abort permissioncondition depending on at least one of them, it is possible toappropriately reflect the driver's intention to abort in the lane changecontrol.

Moreover, depending on the purpose of the lane change, it is sometimespreferable not to comply with the driver's intention to abort but togive priority to the lane change control. By changing the ease ofsatisfaction of the abort permission condition depending on the purposeof the lane change, it is possible to appropriately continue andcomplete the lane change.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual diagram for explaining lane change control by anautonomous driving system according to an embodiment of the presentdisclosure;

FIG. 2 is a conceptual diagram for explaining an abort request operationby a driver in the embodiment of the present disclosure;

FIG. 3 is a diagram showing various examples of variable setting of anabort permission condition in the embodiment of the present disclosure;

FIG. 4 is a block diagram schematically showing a configuration of theautonomous driving system according to the embodiment of the presentdisclosure;

FIG. 5 is a block diagram showing a configuration example of a lanechange control device according to the embodiment of the presentdisclosure;

FIG. 6 is a block diagram showing an example of driving environmentinformation used in the lane change control device according to theembodiment of the present disclosure;

FIG. 7 is a flow chart showing lane change control processing by thelane change control device according to the embodiment of the presentdisclosure;

FIG. 8 is a conceptual diagram for explaining a first example of StepS40 (condition determination processing) of the lane change controlprocessing according to the embodiment of the present disclosure;

FIG. 9 is a flow chart showing the first example of Step S40 (conditiondetermination processing) of the lane change control processingaccording to the embodiment of the present disclosure;

FIG. 10 is a conceptual diagram for explaining a second example of StepS40 (condition determination processing) of the lane change controlprocessing according to the embodiment of the present disclosure;

FIG. 11 is a flow chart showing the second example of Step S40(condition determination processing) of the lane change controlprocessing according to the embodiment of the present disclosure;

FIG. 12 is a flow chart showing a third example of Step S40 (conditiondetermination processing) of the lane change control processingaccording to the embodiment of the present disclosure; and

FIG. 13 is a conceptual diagram for explaining an example of returncontrol in Step S50 (abort processing) of the lane change controlprocessing according to the embodiment of the present disclosure.

EMBODIMENTS

Embodiments of the present disclosure will be described below withreference to the attached drawings.

1. Outline

FIG. 1 is a conceptual diagram for explaining lane change control by anautonomous driving system 10 according to the present embodiment. Theautonomous driving system 10 is mounted on a vehicle 1 and controlsautonomous driving of the vehicle 1. The autonomous driving controlincludes “lane change control” for changing a travel lane in which thevehicle 1 travels. For example, the autonomous driving system 10performs the lane change control in order to overtake a precedingvehicle 2. A purpose of the lane change is exemplified not only byovertaking but also by lane merging, lane branching, obstacle avoidance,and so forth.

In the following description, the original travel lane before the lanechange is referred to as a “first lane L1”. The travel lane after thelane change, that is, a target lane of the lane change is referred to asa “second lane L2”. That is, the autonomous driving system 10 performsthe lane change control for making a lane change from the first lane Lto the second lane L2 during the autonomous driving of the vehicle 1. Adirection from the first lane L1 to the second lane L2 is hereinafterreferred to as a “lane change direction DLC”.

It should be noted that the lane change control according to the presentembodiment is not limited only to steering control for moving thevehicle 1 from the first lane L1 to the second lane L2. For example,turn signal flashing before start of the steering control also isincluded in the lane change control according to the present embodiment.Moreover, positioning that accelerates or decelerates the vehicle 1 tomove the vehicle 1 to a suitable position for the lane change beforestarting the steering control also is included in the lane changecontrol according to the present embodiment. The turn signal flashingand the positioning performed before the steering control is hereinafterreferred to as “preliminary control”. It is also possible that theautonomous driving system 10 proposes execution of the lane change to adriver of the vehicle 1 and the driver approves the proposed lanechange. In that case, a series of control performed after the driver'sapproval is included in the lane change control.

The autonomous driving system 10 according to the present embodiment isdesigned such that the driver can abort (cancel) the lane change controlafter start of the lane change control. An operation performed by thedriver to request the autonomous driving system 10 to abort the lanechange control is hereinafter referred to as an “abort request operationAR”.

FIG. 2 is a conceptual diagram for explaining the abort requestoperation AR by the driver. In FIG. 2, an “abort direction DAB” is adirection from the second lane L2 to the first lane L1, that is,opposite to the lane change direction DLC. As an example of the abortrequest operation AR, the driver operates a turn signal lever toindicate the abort direction DAB (i.e. the abort request operationAR=turn signal lever operation). As another example, the driver steers asteering wheel in the abort direction DAB (i.e. the abort requestoperation AR=steering operation). From start to completion of the lanechange control, the autonomous driving system 10 determines whether ornot the abort request operation AR is performed by the driver.

It should be noted that even when the abort request operation AR isperformed, the lane change control is not always aborted. When the abortrequest operation AR is performed, the autonomous driving system 10further determines whether or not an “abort permission condition” issatisfied. The abort permission condition is a condition for determiningwhether or not to accept (comply with) the abort request from thedriver. When the abort permission condition is not satisfied, theautonomous driving system 10 continues the lane change control withoutaccepting the abort request from the driver. On the other hand, when theabort permission condition is satisfied, the autonomous driving system10 accepts the abort request from the driver and aborts the lane changecontrol. When the lane change control is aborted, the autonomous drivingsystem 10 makes the vehicle 1 travel in the original first lane L1.

When the driver's intention to abort is considered to be strong, it ispreferable to accept the abort request from the driver as much aspossible. On the other hand, when a necessity level of the lane changeis considered to be high, it is preferable to continue the lane changecontrol without accepting the abort request from the driver. Therefore,according to the present embodiment, the above-described abortpermission condition is not fixed but variably set depending on thesituation.

FIG. 3 is a diagram showing various examples of variable setting of theabort permission condition in the present embodiment. The autonomousdriving system 10 changes ease of satisfaction of the abort permissioncondition depending on the situation.

For example, the autonomous driving system 10 changes the ease ofsatisfaction of the abort permission condition depending on a “type ofthe abort request operation AR”. As an example, let us consider twotypes of the abort request operation AR, that is, the turn signal leveroperation and the steering operation described above. The turn signallever operation is considered to represent the driver's strong intentionto abort. On the other hand, the driver's intention to abort in the caseof the steering operation is considered to be weaker than the driver'sintention to abort in the case of the turn signal lever operation.Moreover, there is a possibility that the steering operation is notperformed for requesting to abort the lane change control but merely foravoiding an adjacent vehicle coming closer. In view of the above, theautonomous driving system 10 sets the abort permission condition in thecase of the turn signal lever operation is set to be more easilysatisfied than the abort permission condition in the case of thesteering operation.

As another example, the autonomous driving system 10 changes the ease ofsatisfaction of the abort permission condition depending on an“operation amount of the abort request operation AR”. More specifically,it is considered that the larger the operation amount of the abortrequest operation AR is, the stronger the driver's intention to abortis. In view of the above, the autonomous driving system 10 sets theabort permission condition to be more easily satisfied as the operationamount of the abort request operation AR becomes larger. For example,let us consider a case where the abort request operation AR is theabove-described steering operation. In this case, the abort permissioncondition becomes more easily satisfied as a steering amount of thesteering wheel becomes larger.

As still another example, the autonomous driving system 10 changes theease of satisfaction of the abort permission condition depending on an“operation speed of the abort request operation AR”. More specifically,it is considered that the higher the operation speed of the abortrequest operation AR is, the stronger the driver's intention to abortis. In view of the above, the autonomous driving system 10 sets theabort permission condition to be more easily satisfied as the operationspeed of the abort request operation AR becomes higher. For example, letus consider a case where the abort request operation AR is theabove-described steering operation. In this case, the abort permissioncondition becomes more easily satisfied as a steering speed of thesteering wheel becomes higher.

As still another example, the autonomous driving system 10 changes theease of satisfaction of the abort permission condition depending on a“purpose of the lane change”. For example, the lane change for lanemerging or lane branching is important for arriving at a destination,and thus the autonomous driving is significantly influenced if such thelane change is aborted. Similarly, the lane change for avoiding anobstacle is important for safety, and thus the autonomous driving issignificantly influenced if such the lane change is aborted. On theother hand, even when the lane change for overtaking a preceding vehicle2 is aborted, the autonomous driving is not so influenced. That is tosay, priority of the lane change for lane merging, lane branching, andobstacle avoidance is high, and priority of the lane change forovertaking is low. In view of the above, the autonomous driving system10 sets the abort permission condition when the purpose of the lanechange is overtaking to be more easily satisfied than the abortpermission condition when the purpose is lane merging, lane branching,or obstacle avoidance.

According to the present embodiment, the abort permission condition isvariably set depending on at least one of “the type of the abort requestoperation AR”, “the operation amount of the abort request operation AR”,“the operation speed of the abort request operation AR”, and “thepurpose of the lane change” exemplified above. A combination of two ormore of them may be considered.

As described above, the autonomous driving system 10 according to thepresent embodiment is configured to be able to handle the abort requestoperation AR by the driver from start to completion of the lane changecontrol. When the abort request operation AR is performed by the driverand the abort permission condition is satisfied, the autonomous drivingsystem 10 aborts the lane change control. As a result, the driver'sintention to abort is reflected in the lane change control by theautonomous driving system 10.

Furthermore, according to the present embodiment, the ease ofsatisfaction of the abort permission condition is changed depending onat least one of “the type of the abort request operation AR”, “theoperation amount of the abort request operation AR”, “the operationspeed of the abort request operation AR”, and “the purpose of the lanechange”. Each of the type, the operation amount, and the operation speedof the abort request operation AR reflects strength of the driver'sintention to abort. By changing the ease of satisfaction of the abortpermission condition depending on at least one of them, it is possibleto appropriately reflect the driver's intention to abort in the lanechange control.

Moreover, depending on the purpose of the lane change, it is sometimespreferable not to comply with the driver's intention to abort but togive priority to the lane change control. By changing the ease ofsatisfaction of the abort permission condition depending on the purposeof the lane change, it is possible to appropriately continue andcomplete the lane change.

2. Configuration Example of Autonomous Driving System

FIG. 4 is a block diagram schematically showing a configuration of theautonomous driving system 10 according to the present embodiment. Theautonomous driving system 10 mounted on the vehicle 1 includes adriver's operation detection device 20 and a lane change control device100.

The driver's operation detection device 20 is a device for detecting anoperation by the driver (hereinafter referred to as a “driver'soperation”). More specifically, the driver's operation detection device20 includes an operation member that the driver operates, and anoperation sensor detecting that the operation member is operated. Theoperation member is exemplified by a turn signal lever and a steeringwheel. The driver's operation detection device 20 detects the driver'soperation based on the operation sensor and transmits information on thedetected driver's operation, as driver's operation information IDO, tothe lane change control device 100.

The driver's operation using the turn signal lever is the “turn signallever operation”. The operation sensor includes a sensor that detectsthe turn signal lever operation. The driver's operation detection device20 transmits information indicating an operation direction of the turnsignal lever, as the driver's operation information IDO, to the lanechange control device 100. The driver's operation using the turn signallever includes the abort request operation AR. More specifically, theabort request operation AR is to operate the turn signal lever toindicate the abort direction DAB.

The driver's operation using the steering wheel is the “steeringoperation”. The operation sensor includes a steering angle sensor thatdetects a steering angle of the steering wheel. Based on a result ofdetection by the steering angle sensor, the driver's operation detectiondevice 20 calculates a steering amount and a steering speed of thesteering wheel. Then, the driver's operation detection device 20transmits information on the calculated steering amount and steeringspeed, as the driver's operation information IDO, to the lane changecontrol device 100. The driver's operation using the steering wheelincludes the abort request operation AR. More specifically, the abortrequest operation AR is to steer the steering wheel in the abortdirection DAB.

The lane change control device 100 performs the lane change controlduring the autonomous driving of the vehicle 1. From start to completionof the lane change control, the lane change control device 100recognizes the driver's operation based on the driver's operationinformation IDO and determines whether or not the driver's operation isperformed as the abort request operation AR. When the abort requestoperation AR is performed, the lane change control device 100 determineswhether or not the abort permission condition is satisfied. When theabort permission condition is not satisfied, the lane change controldevice 100 continues the lane change control. On the other hand, whenthe abort permission condition is satisfied, the lane change controldevice 100 aborts the lane change control and makes the vehicle 1 travelin the first lane L1.

FIG. 5 is a block diagram showing a configuration example of the lanechange control device 100 according to the present embodiment. The lanechange control device 100 is provided with a GPS (Global PositioningSystem) receiver 110, a map database 120, a sensor group 130, acommunication device 140, an HMI (Human Machine Interface) unit 150, atravel device 160, and a control device 170.

The GPS receiver 110 receives signals transmitted from a plurality ofGPS satellites and calculates a position and an orientation of thevehicle 1 based on the received signals.

Map information is recorded in the map database 120. The map informationincludes information of a lane geometry (i.e. lane position, lane shape,and lane orientation).

The sensor group 130 detects a situation around the vehicle 1 and atravel state of the vehicle 1. The sensor group 130 is exemplified by aLIDAR (Laser Imaging Detection and Ranging), a radar, a camera, avehicle speed sensor, and the like. The LIDAR uses laser lights todetect a target around the vehicle 1. The radar uses radio waves todetect a target around the vehicle 1. The camera images a situationaround the vehicle 1. The vehicle speed sensor detects a speed of thevehicle 1

The communication device 140 communicates with the outside of thevehicle 1. For example, the communication device 140 performs a V2Icommunication (a vehicle-to-infrastructure communication) with asurrounding infrastructure. The communication device 140 may perform aV2V communication (a vehicle-to-vehicle communication) with asurrounding vehicle. In addition, the communication device 140 maycommunicate with a management server managing autonomous driving servicethrough a communication network.

The HMI unit 150 is an interface for proving the driver with informationand receiving information from the driver. More specifically, the HMIunit 150 includes an input device and an output device. The input deviceis exemplified by a touch panel, a switch, a microphone, and the like.The output device is exemplified by a display device, a speaker, and thelike. The output device is, for example, used by the autonomous drivingsystem 10 (the lane change control device 100) for proposing a lanechange to the driver. The input device is used by the driver forapproving or refusing the proposed lane change.

The travel device 160 includes a steering device, a driving device, abraking device, and so forth. The steering device turns wheels. Thedriving device is a power source that generates a driving force. Thedriving device is exemplified by an engine and an electric motor. Thebraking device generates a braking force.

The control device 170 controls the autonomous driving of the vehicle 1.The control device 170 is a microcomputer including a processor 171 anda memory device 172. The control device 170 is also called an ECU(Electronic Control Unit). The autonomous driving control by the controldevice 170 is achieved by the processor 171 executing a control programstored in the memory device 172.

More specifically, the control device 170 acquires information necessaryfor the autonomous driving control. The autonomous driving controlrequires information indicating driving environment for the vehicle 1,and the information is hereinafter referred to as “driving environmentinformation 200”. The driving environment information 200 is stored inthe memory device 172, and read out and used as appropriate.

FIG. 6 shows an example of the driving environment information 200 inthe present embodiment. The driving environment information 200 includesposition-orientation information 210, map information 220,sensor-detected information 230, and delivery information 240.

The position-orientation information 210 indicates the position and theorientation of the vehicle 1. The control device 170 acquires theposition-orientation information 210 from the GPS receiver 110.

The map information 220 includes information of the lane geometry (i.e.lane position, lane shape, and lane orientation). The control device 170acquires the map information 220 around the vehicle 1 based on theposition-orientation information 210 and the map database 120. Based onthe map information 220, the control device 170 can recognize lanemerging, lane branching, intersections, and so forth.

The sensor-detected information 230 is information acquired based on aresult of detection by the sensor group 130. More specifically, thesensor-detected information 230 includes target information regarding atarget around the vehicle 1. The target around the vehicle 1 isexemplified by a surrounding vehicle, a pedestrian, a roadsidestructure, a white line, a traffic sign, and so forth. The targetinformation includes a relative position, a relative speed, and the likeof the detected target. In addition, the sensor-detected information 230includes the vehicle speed detected by the vehicle speed sensor. Thecontrol device 170 acquires the sensor-detected information 230 based onthe result of detection by the sensor group 130.

The delivery information 240 is information acquired through thecommunication device 140. For example, the delivery information 240includes road traffic information (roadwork section information,accident information, traffic regulation information, traffic jaminformation, and the like) delivered from the infrastructure. Thedelivery information 240 may include information delivered from themanagement server managing the autonomous driving service. The controldevice 170 acquires the delivery information 240 by using thecommunication device 140 to communicate with the outside of the vehicle1.

The control device 170 controls the autonomous driving of the vehicle 1based on the driving environment information 200 indicating the drivingenvironment. More specifically, the control device 170 creates a travelplan of the vehicle 1 based on the driving environment information 200.Then, the control device 170 controls the travel device 160 to make thevehicle 1 travel in accordance with the travel plan.

The autonomous driving control by the control device 170 includes the“lane change control” described above. Hereinafter, the lane changecontrol by the lane change control device 100 (i.e. the control device170) according to the present embodiment will be described in moredetail.

3. Processing Flow of Lane Change Control

FIG. 7 is a flow chart showing lane change control processing by thelane change control device 100 according to the present embodiment.

3-1. Step S10

The lane change control device 100 plans a lane change based on thedriving environment information 200. The purpose of the lane changeincludes lane merging, lane branching, obstacle avoidance, overtaking apreceding vehicle 2, and so forth.

When the purpose of the lane change is the lane merging, typically, thefirst lane L1 is a merge lane and the second lane L2 is a main line.Moreover, the lane merging includes a case where the first lane L1 (forexample, a slower traffic lane) disappears in front. When the purpose ofthe lane change is the lane branching, typically, the first lane L1 is amain line and the second lane L2 is a branch lane leading to adestination. Moreover, the lane branching includes a case of making alane change in advance to a lane adjacent to the branch lane in order toenter the branch lane in front. The lane change for the lane merging andthe lane branching is planned based on the destination, theposition-orientation information 210, and the map information 220.

The obstacle is exemplified by a roadwork section, an accident vehicle,and a merged section. The roadwork section and the accident vehicle canbe recognized based on the delivery information 240 (the road trafficinformation) or the sensor-detected information 230 (the targetinformation). The merged section can be recognized based on the mapinformation 220. The preceding vehicle 2 as a target of the overtakingis determined based on the sensor-detected information 230 (the targetinformation and the vehicle speed information).

3-2. Step S20

In order to achieve the lane change planned in Step S10, the lane changecontrol device 100 starts the lane change control. Here, the lane changecontrol is not limited only to the steering control for moving thevehicle 1 from the first lane L1 toward the second lane L2. Thepreliminary control such as the positioning (accelerating/decelerating)and the turn signal flashing before start of the steering control alsois included in the lane change control. The lane change control device100 controls the travel device 160 to perform the positioning and thesteering control.

Before starting the lane change control, the lane change control device100 may propose execution of the lance change to the driver through theoutput device of the HMI unit 150. In this case, the driver uses theinput device of the HMI unit 150 to approve or refuse the proposed lanechange.

3-3. Step S30 (Abort Request Detection Processing)

From start to completion of the lane change control, the lane changecontrol device 100 performs abort request detection processing thatdetermines whether or not the driver's operation by the driver isperformed as the abort request operation AR. The abort request detectionprocessing is performed based on the driver's operation information IDOreceived from the driver's operation detection device 20.

For example, when the turn signal lever is operated to indicate theabort direction DAB for more than a reference time, it is determinedthat the turn signal lever operation is performed as the abort requestoperation AR. As another example, when the steering wheel is steered inthe abort direction DAB by more than a reference steering amount, it isdetermined that the steering operation is performed as the abort requestoperation AR. As still another example, when the steering wheel issteered in the abort direction DAB at a steering speed of more than areference speed, it is determined that the steering operation isperformed as the abort request operation AR.

When the abort request operation AR is performed (Step S30; Yes), theprocessing proceeds to Step S40. On the other hand, when the abortrequest operation AR is not performed (Step S30; No), the processingproceeds to Step S60.

3-4. Step S40 (Condition Determination Processing)

The lane change control device 100 performs condition determinationprocessing that determines whether or not the abort permission conditionis satisfied. Here, the lane change control device 100 changes (variablysets) the ease of satisfaction of the abort permission conditiondepending on the situation.

More specifically, the lane change control device 100 changes the easeof satisfaction of the abort permission condition depending on at leastone of the type of the abort request operation AR, the operation amountof the abort request operation AR, the operation speed of the abortrequest operation AR, and the purpose of the lane change (see FIG. 3).The type, the operation amount, and the operation speed of the abortrequest operation AR can be recognized based on the driver's operationinformation IDO. The purpose of the lane change is that planned at theabove-described Step S10. Various examples can be considered as a methodof setting and changing the abort permission condition, which will bedescribed later in detail.

When the abort permission condition is satisfied (Step S40; Yes), theprocessing proceeds to Step S50. On the other hand, when the abortpermission condition is not satisfied (Step S40; No), the processingproceeds to Step S60.

3-5. Step S50 (Abort Processing)

The lane change control device 100 aborts the lane change control. Then,the lane change control device 100 makes the vehicle 1 travel in theoriginal first lane L1.

In particular, when the abort request operation AR is performed afterthe vehicle 1 overlaps the second lane L2 and when the abort permissioncondition is satisfied, the lane change control device 100 performs“return control”. The return control is vehicle control that makes thevehicle 1 return from the second lane L2 to the original first lane L1.[0074.]

3-6. Step S60 (Continuation Processing)

The lane change control device 100 continues the lane change control.After that, the processing proceeds to Step S70.

3-7. Step S70

The lane change control device 100 determines whether or not the lanechange control is completed. When the lane change control is not yetcompleted (Step S70; No), the processing returns back to Step S30. Whenthe lane change control is completed (Step S70; Yes), the processingflow shown in FIG. 7 ends.

4. Various Examples of Step S40

Hereinafter, various examples of the above-described Step S40 (i.e. thecondition determination processing) will be described.

4-1. First Example

FIG. 8 is a conceptual diagram for explaining setting of the abortpermission condition in the first example. In the first example, an“abort-permitted region Ra” and an “abort-prohibited region Rb” areused. The abort-permitted region Ra is a region where abort of the lanechange control is permitted. On the other hand, the abort-prohibitedregion Rb is a region where abort of the lane change control is notpermitted.

In the example shown in FIG. 8, a sum of a width of the first lane L1and a width of the second lane L2 is denoted by “d0”. Theabort-permitted region Ra is a region on the side of the first lane L1and with a width da among the total width d0. On the other hand, theabort-prohibited region Rb is a region on the side of the second lane L2and with a width db among the total width d0. When considering adistribution ratio r1 (0≤r1≤1), the width da of the abort-permittedregion Ra and the width db of the abort-prohibited region Rb areexpressed by the following Equation (1).

da=r1×d0

db=d0−da  Equation (1):

The abort permission condition in the first example is that “the vehicle1 is inside the abort-permitted region Ra”, in other words, “the vehicle1 is outside the abort-prohibited region Rb”. By increasing thedistribution ratio r1, it is possible to expands the abort-permittedregion Ra to increase the ease of satisfaction of the abort permissioncondition. Conversely, by decreasing the distribution ratio r1, it ispossible to narrow the abort-permitted region Ra to decrease the ease ofsatisfaction of the abort permission condition.

FIG. 9 is a flow chart showing S40 (i.e. the condition determinationprocessing) in the case of the first example.

Step S41:

First, the lane change control device 100 sets the abort-permittedregion Ra. The geometry (shape, width, etc.) of each of the first laneL1 and the second lane L2 can be obtained from the map information 220or the sensor-detected information 230 (detected white lineinformation).

As described above, the lane change control device 100 changes the easeof satisfaction of the abort permission condition depending on thesituation. When increasing the ease of satisfaction of the abortpermission condition, the lane change control device 100 increases thedistribution ratio r1 to expand the abort-permitted region Ra. On theother hand, when decreasing the ease of satisfaction of the abortpermission condition, the lane change control device 100 decreases thedistribution ratio r1 to narrow the abort-permitted region Ra. Thedistribution ratio r1 which is changed depending on the situation isgiven, for example, by a map created in advance.

Step S42:

The lane change control device 100 determines whether or not the vehicle1 is inside the abort-permitted region Ra. For example, a centerposition of the vehicle 1 when seen from the above is used as theposition of the vehicle 1. Based on the position-orientation information210 and the map information 220 or the sensor-detected information 230(detected white line information), the lane change control device 100determines whether or not the vehicle 1 is inside the abort-permittedregion Ra.

When the vehicle 1 is inside the abort-permitted region Ra (Step S42;Yes), it is determined that the abort permission condition is satisfied(Step S40; Yes). On the other hand, when the vehicle 1 is not inside theabort-permitted region Ra (Step S42; No), it is determined that theabort permission condition is not satisfied (Step S40; No).

4-2. Second Example

FIG. 10 is a conceptual diagram for explaining setting of the abortpermission condition in the second example. In the second example, a“congestion level C” of a surrounding vehicle 3 traveling in the firstlane L1 is used.

For example, a congestion level calculation region Rc is a region withina certain distance ahead of and behind the vehicle 1, and thesurrounding vehicle 3 existing in the congestion level calculationregion Rc is recognized. The surrounding vehicle 3 can be recognizedbased on the sensor-detected information 230 (the target information).Subsequently, an inter-vehicle distance λ between the vehicle 1 and thesurrounding vehicle 3 is calculated with respect to each surroundingvehicle 3 recognized. A minimum value of the calculated inter-vehicledistances L is a minimum inter-vehicle distance λmin. The congestionlevel C is represented by reciprocal of the minimum inter-vehicledistance min, as shown in the following equation (2).

C=1/λmin  Equation (2):

The congestion level C increases as the minimum inter-vehicle distanceλmin decreases. Alternatively, an average inter-vehicle distance λavebeing an average value of the calculated inter-vehicle distances λ maybe used instead of the minimum inter-vehicle distance λmin.

The abort permission condition in the second example is that “thecongestion level C is less than a threshold Cth”. When the congestionlevel C is high, it is preferable to continue the lane change controlwithout returning the vehicle 1 to the first lane L1. However, when thethreshold Cth is set to be high, abort of the lane change control ispermitted even if the congestion level C in the first lane L1 issomewhat high. That is, by increasing the threshold Cth, it is possibleto increase the ease of satisfaction of the abort permission condition.Conversely, by decreasing the threshold Cth, it is possible to decreasethe ease of satisfaction of the abort permission condition.

FIG. 11 is a flow chart showing S40 (i.e. the condition determinationprocessing) in the case of the second example.

Step S43:

The lane change control device 100 sets the threshold Cth. As describedabove, the lane change control device 100 changes the ease ofsatisfaction of the abort permission condition depending on thesituation. When increasing the ease of satisfaction of the abortpermission condition, the lane change control device 100 increases theincreases the threshold Cth. On the other hand, when decreasing the easeof satisfaction of the abort permission condition, the lane changecontrol device 100 decreases the threshold Cth. The threshold Cth whichis changed depending on the situation is given, for example, by a mapcreated in advance.

Step S44:

The lane change control device 100 calculates the congestion level C.More specifically, based on the sensor-detected information 230 (thetarget information), the lane change control device 100 recognizes thesurrounding vehicle 3 existing in the congestion level calculationregion Re to calculate the congestion level C.

Step S45:

The lane change control device 100 determines whether or not thecongestion level C is less than the threshold Cth. When the congestionlevel C is less than the threshold Cth (Step S45; Yes), it is determinedthat the abort permission condition is satisfied (Step S40; Yes). On theother hand, when the congestion level C is equal to or greater than thethreshold Cth (Step S45; No), it is determined that the abort permissioncondition is not satisfied (Step S40; No).

4-3. Third Example

FIG. 12 is a flow chart showing a third example of Step S40 (i.e. thecondition determination processing). The third example is a combinationof the first example and the second example described above. When it isdetermined in Step S42 that the vehicle 1 is inside the abort-permittedregion Ra (Step S42; Yes), the processing proceeds to Step S43. Theothers are the same as in the cases of the first example and the secondexample.

5. Example of Return Control

In the above-described Step S50, the lane change control device 100aborts the lane change control and makes the vehicle 1 travel in theoriginal first lane L1. In particular, when the abort request operationAR is performed after the vehicle 1 overlaps the second lane L2 and whenthe abort permission condition is satisfied, the lane change controldevice 100 performs “return control”. The return control is vehiclecontrol that makes the vehicle 1 return from the second lane L2 to theoriginal first lane L1. It is also possible to change a method of thereturn control depending on the situation.

FIG. 13 is a conceptual diagram for explaining an example of the returncontrol. A travel path of the vehicle 1 in the return control (that is,a travel path when the vehicle 1 returns from the second lane L2 to thefirst lane L1) is hereinafter referred to as a “return path PR”. In thereturn control, the lane change control device 100 calculates the returnpath PR and controls the travel device 160 such that the vehicle 1travels along the return path PR. The lane change control device 100changes a length of the return path PR depending on the type of theabort request operation AR (the turn signal lever operation or thesteering operation).

More specifically, when the abort request operation AR is the turnsignal lever operation, the driver's intention to abort is strong.Therefore, a comparatively short return path PRs is used in order topromptly return the vehicle 1 to the first lane L1. On the other hand,when the abort request operation AR is the steering operation, acomparatively long return path PR1 is used in order to suppress rapidvehicle behavior. That is to say, the return path PRs when the abortrequest operation AR is the turn signal lever operation is shorter thanthe return path PR1 when the abort request operation AR is the steeringoperation. By changing the return path PR depending on the type of theabort request operation AR in this manner, it is possible to realizeappropriate vehicle behavior reflecting the driver's intention.

As another example, the lane change control device 100 may changeacceleration/deceleration of the vehicle 1 generated in the returncontrol (hereinafter referred to as “return acceleration/deceleration”),depending on the type of the abort request operation AR.

More specifically, when the abort request operation AR is the turnsignal lever operation, the return acceleration/deceleration is set tobe comparatively high in order to quickly return the vehicle 1 to thefirst lane L1. On the other hand, when the abort request operation AR isthe steering operation, the return acceleration/deceleration is set tobe comparatively low in order to suppress rapid vehicle behavior. Thatis to say, the return acceleration/deceleration when the abort requestoperation AR is the turn signal lever operation is higher than thereturn acceleration/deceleration when the abort request operation AR isthe steering operation. By changing the return acceleration/decelerationdepending on the type of the abort request operation AR in this manner,it is possible to realize appropriate vehicle behavior reflecting thedriver's intention.

What is claimed is:
 1. An autonomous driving system mounted on avehicle, comprising: a lane change control device that performs lanechange control for making a lane change from a first lane to a secondlane during autonomous driving of the vehicle; and a driver's operationdetection device that detects a driver's operation by a driver of thevehicle, wherein the lane change control device performs: abort requestdetection processing that, from start to completion of the lane changecontrol, determines whether or not the driver's operation is performedas an abort request operation that requests to abort the lane changecontrol; condition determination processing that, when the abort requestoperation is performed, determines whether or not an abort permissioncondition is satisfied; continuation processing that, when the abortpermission condition is not satisfied, continues the lane changecontrol; and abort processing that, when the abort permission conditionis satisfied, aborts the lane change control and makes the vehicletravel in the first lane, wherein the lane change control device changesease of satisfaction of the abort permission condition depending on atleast one of a type of the abort request operation, an operation amountof the abort request operation, an operation speed of the abort requestoperation, and a purpose of the lane change.
 2. The autonomous drivingsystem according to claim 1, wherein the lane change control devicechanges the ease of satisfaction of the abort permission conditiondepending on the type of the abort request operation.
 3. The autonomousdriving system according to claim 2, wherein: the driver's operationdetection device includes a turn signal lever and a steering wheel; andthe abort permission condition when the turn signal lever is used forthe abort request operation is more easily satisfied than the abortpermission condition when the steering wheel is used for the abortrequest operation.
 4. The autonomous driving system according to claim3, wherein: a direction from the second lane to the first lane is anabort direction; the abort request operation using the turn signal leveris to operate the turn signal lever to indicate the abort direction; andthe abort request operation using the steering wheel is to steer thesteering wheel in the abort direction.
 5. The autonomous driving systemaccording to claim 3, wherein: when the abort request operation isperformed after the vehicle overlaps the second lane and when the abortpermission condition is satisfied, the lane change control deviceperforms return control that makes the vehicle return from the secondlane to the first lane; a travel path of the vehicle in the returncontrol is a return path; and the return path when the turn signal leveris used for the abort request operation is shorter than the return pathwhen the steering wheel is used for the abort request operation.
 6. Theautonomous driving system according to claim 3, wherein: when the abortrequest operation is performed after the vehicle overlaps the secondlane and when the abort permission condition is satisfied, the lanechange control device performs return control that makes the vehiclereturn from the second lane to the first lane; acceleration/decelerationof the vehicle in the return control is returnacceleration/deceleration; and the return acceleration/deceleration whenthe turn signal lever is used for the abort request operation is higherthan the return acceleration/deceleration when the steering wheel isused for the abort request operation.
 7. The autonomous driving systemaccording to claim 1, wherein the lane change control device changes theease of satisfaction of the abort permission condition depending on theoperation amount or the operation speed of the abort request operation.8. The autonomous driving system according to claim 7, wherein: adirection from the second lane to the first lane is an abort direction;the driver's operation detection device includes a steering wheel; theabort request operation is to steer the steering wheel in the abortdirection; and the abort permission condition becomes more easilysatisfied as a steering amount of the steering wheel becomes larger or asteering speed of the steering wheel becomes higher.
 9. The autonomousdriving system according to claim 1, wherein the lane change controldevice changes the ease of satisfaction of the abort permissioncondition depending on the purpose of the lane change.
 10. Theautonomous driving system according to claim 9, wherein the abortpermission condition when the purpose is overtaking is more easilysatisfied than the abort permission condition when the purpose is lanemerging, lane branching, or obstacle avoidance.
 11. The autonomousdriving system according to claim 1, wherein: an abort-permitted regionis a region where abort of the lane change control is permitted; theabort permission condition is that the vehicle is inside theabort-permitted region; when increasing the ease of satisfaction of theabort permission condition, the lane change control device expands theabort-permitted region; and when decreasing the ease of satisfaction ofthe abort permission condition, the lane change control device narrowsthe abort-permitted region.
 12. The autonomous driving system accordingto claim 1, wherein: the abort permission condition is that a congestionlevel of a surrounding vehicle traveling in the first lane is less thana threshold; when increasing the ease of satisfaction of the abortpermission condition, the lane change control device increases thethreshold; and when decreasing the ease of satisfaction of the abortpermission condition, the lane change control device decreases thethreshold.